In the field of optical materials and electronic materials, an improvement in an integration degree, higher density in an information amount, and higher definition of image information are required. Therefore, it is necessary to form a fine structure (hereinafter referred to as a fine-pattern structure) in the film used in such field. Especially, in regenerative medicine, the film having the fine-pattern structure on the surface is effective as a cell culture substrate (see. Japanese Patent Laid-Open Publication No. 2001-157574).
As a method for forming the fine-pattern structure in the film, a deposition method using a mask, photolithography technology using photochemical reaction and polymerization reaction, laser ablation technology and so forth come into practical use.
It is known to obtain a film having a honeycomb structure of on the micron scale by casting dilute solution of polymer, which has a special structure, under a high-humidity condition (see. Japanese Patent Laid-Open Publication No. 2002-335949). Functional particles are contained in that film, so that the film is used as the optical and electronic materials. For instance, the film is used as a display device by containing light-emitting material (see. Japanese Patent Laid-Open Publication No. 2003-128832).
The film in which the fine-pattern structure is formed is also used in a polarizing filter. As such a film, there is a film having a moth-eye structure for developing an antireflective function. The fine pattern having a size from submicron to several tens of microns is regularly formed in that film. In a mainstream method for forming the fine pattern, the structure of a plate, which is made by using micro-processing technique, for instance the photolithography, is transferred on the film (see. Japanese Patent Laid-Open Publication No. 2003-302532).
The method described in Japanese Patent Laid-Open Publication No. 2003-302532 is called a top-down approach to make the plate for determining the fine structure. Many complicate procedures are required to make the plate, and the cost is increased. Additionally, it is difficult to make the plate having a large area.
An object of the present invention is to provide a method for producing continuously or intermittently a large area film having a uniform honeycomb or moth-eye structure at low cost.